Rough running kohler command 20

I have a Walker GHS mower with a Kohler Command 20 engine. It has about 600 hours on it. It just started to run rough, lack power, spit, sputter, and occasional light backfire/miss while running......almost acts like it is partially choked. Is this a common problem with these engines? Filters, plugs, fuels, etc. have always been maintained properly.

I am going to start by replacing the gas filter, air filter, and plugs. If this doesn't help where should I look next? This Problem started after some heavy mowing which really put a load on the machine. Is there a possibility of overheating problems......possibly burnt valves???

Thanks for the hints. I didn't see any water in the gas or the filter, although there was a lot of fine trash in the gas tank. It isn't the seat switch since it does it without the blade engaged. The choke plate position and linkage is O.K.

Is it relatively simple to take this carb apart and get it back together? Maybe I should try that. Any additional hints would be appreciated.

I had a simular problem last year. I tried everything and then finally replaced the entire fuel line. It seems that the inside of the fuel line had collaped or become narrow and it was not letting sufficient fuel flow through. My mower would start and run fine for a minute and then start acting like the choke was pulled or it was running out of fuel. The new fuel line fixed it.

Also you might check the needle and seat if you have not already done so. If the seat in the carb is bad it may load up with fuel.

My 18 Kohler is starting to run rough once it gets good and hot, mainly after it gets hot and then I shut it down and start it up again. Then it acts like it's running on one cylinder. I don't know if this is the problem you are having or not. My dealer says it's probally the coils.